1. Field of the Invention
The present invention relates to flexible substrates applicable to LED products, and, more particularly, to a thin metal substrate having high thermal conductivity.
2. Description of Related Art
Although LED products have advantages of energy-saving, high efficiency, fast response time and long lifetime, and do not contain mercury that is harmful to the environment, the LED products convert only about 20% of input power into light, with the remaining being converted into heat.
If heat generated by an LED product cannot be timely dissipated out, it can result in a too high junction temperature, thus adversely affecting the lifetime, light emitting efficiency and stability of the LED.
Generally, a conventional thermal conductive adhesive that is attached to a copper layer has a thickness of 60-120 um for meeting insulating requirements. This increases the overall thickness of the product and leads to an undesirable heat dissipating effect. In view of these drawbacks, a heat dissipating model of TPI (thermoplastic polyimide) mixed with a thermal conductive powder is used to reduce the overall thickness of the product and achieve a preferred insulating characteristic. However, TPI needs to be processed at a high temperature greater than 350° C., which significantly increases the processing cost and is not suitable for mass production.
Taiwan Patent No. M377823 discloses a composite double-sided copper-clad substrate. But the heat dissipating efficiency and insulating performance of the substrate need to be improved.